Grain is generally harvested using a combine. The combine separates the grain from the leafy portion of the plant and other residue and stores the grain in a hopper, or bin, in the combine. The grain is then typically off-loaded from the combine by means of an auger into a grain cart for temporary storage prior to transport to an elevator. In most cases, the grain cart is drawn by a tractor alongside the combine during grain off-loading in an "on-the-go" manner to eliminate combine down-loading time.
Ideally, grain cart capacity should be as large as possible to minimize interruptions in combine operation for off-loading of the grain. However, grain cart size is limited by practical considerations such as the size of the tractor pulling the cart and the condition of the fields in which the cart operates including such factors as wetness, surface irregularities and slope.
Grain carts are typically of the four wheel or two wheel type. A four wheel grain cart typically includes a pivoting tongue attached to the two forward wheels to provide a grain cart steering capability. Four wheel grain carts without a steering capability suffer from limited mobility and are difficult to maneuver particularly in uneven soil conditions such as encountered when ridge tilling is employed. For example, turning a cart without steering causes its forward wheels to pivot about a turning axis in one direction and its aft wheels to pivot about this axis in an opposite direction. As a result, tire "scrubbing" occurs wherein the tire is pulled over the soil surface in a direction not in the plane of the tire which prevents the tire from rotating. Tire scrubbing increases the pulling force required of the tractor to which the grain cart is attached, stresses bearings and other cart components, and breaks down soil ridges when this type of tillage is employed resulting in increased erosion. In addition, tire scrubbing causes excessive tire wear and considerable expense to the farmer because of the high cost of grain cart tires.
Single axle grain carts having a wheel on each side of the cart do not suffer from tire scrubbing as the cart is turned. In this case, the cart's axle is aligned with its turning axis. However, larger grain carts having a single axle and employing a walking tandem wheel arrangement wherein a pair of wheels is disposed fore and aft on each side of the cart are more difficult to maneuver particularly over uneven soil primarily because of tire scrubbing. The present invention is intended to eliminate this limitation in single axle grain cart maneuverability and mobility by providing a single axis grain cart with equalizing dual wheels.